'Good' Bacteria: Good for Colds?

Nov. 7, 2005 - "Eat your bacteria," is not something you hear every day, but it could prove to be good advice for people who want to stay healthy.

During the past few years, interest in the health benefits of probiotics or so-called "good" bacteria has grown. Found in certain yogurts and in supplement form, probiotics are increasingly used to treat diarrhea and other gastrointestinal ailments.

Now a new study suggests that they may also help prevent respiratory infections like the common cold.

Researchers in Sweden compared workers who took the probiotic bacteria Lactobacillus reuteri every day with those who didn't. The workers who took the probiotic had less than half the sick leave of workers who didn't.

The study was paid for by BioGaia AB, the Swedish biotechnology company that markets a line of L. reuteri products.

Good Bugs

There are more than 400 species of bacteria in the human digestive tract, and it is commonly believed that at least some of these help prevent illness by keeping sickness-causing bacteria from flourishing.

The "good bug" theory has been bolstered by research showing that the immune systems of animals brought up in completely germ-free environments do not fully develop, and that such a protected environment promotes, rather than prevents, illness.

The newly published study from Sweden included 181 factory workers who consumed a drink containing L. reuteri or a drink without the probiotic for 80 days.

Twenty-three of the 87 workers in the placebo group reported taking sick days during the study, compared with only 10 of the 94 workers who took the L. reuteri.

The difference was most dramatic among 53 shift workers: none of the 26 shift workers in the L. reuteri group reported taking any sick leave, compared with nine out of 27 shift workers in the placebo group.

Buyer Beware

The study is not the first to suggest that probiotics help protect against respiratory, as well as gastrointestinal disease. In a 2001 study, children who drank milk containing the probiotic Lactobacillus GG were found to have fewer respiratory infections than children who didn't.